The present invention is concerned with a plant extract based on glycerides, a method for the preparation of this extract, as well as a cosmetic composition and a food composition containing said extract.
The most common of glycolipids is the di-O-D-galactosyl-di-O-acylglyceride, also called GalDAG or, more often, Dgdg, which constitutes from 30 to 40% in weight of lipid, membranes. This glyceride was isolated in 1967 by chromatography from human brain and from spinach leaves.
Specifically, the 2,3-di-O-(fatty acid acyl)-1-O-[6xe2x80x2-O-xcex1-D-galactopyranosyl-xcex2-galactopyranosyl]-D-glycerine is described by the following formula: 
wherein R1 and R2 are acyl groups derived from fatty acids and are selected from linoleyl, palmityl, oleyl and stearyl.
Now, the present inventor has shown that these glycolipids and, more particularly, plant extracts containing Dgdg bound to phytosphingolipids and to phospholipids exhibit moisturising properties, elastase inhibiting properties and collagenase inhibiting properties, wound-healing properties, free radical scavenging properties and they can be used as a vector for introducing bound active ingredients into the intercellular space of skin conjunctive tissue. These properties are particularly useful in cosmetics compositions used for skin, mucosa and hair care, as well as in food compositions and/or dietetic compositions.
Further, the di-O-D-galactosyl-di-O-acylglyceride offers the advantage that it originates from the vegetal kingdom, which eliminates the drawbacks associated with the use of products originating from the animal kingdom, in particular the risks arising from bovine diseases (mad cow disease) caused by certain types of prions which, under specific conditions not yet fully elucidated can cause in humans the Creutzfeld-Jakob disease.
Accordingly, a first object of the present invention is a plant extract which contains a mixture of di-O-D-galactosyl-di-O-acylglyceride with phytosphingolipids and phospholipids.
The second object of this invention is a method for obtaining said vegetal extracts, which is characterised in that it comprises a physical extraction operation in which water and ethanol are the solvent which is used.
Finally a further object of the present invention is to provide a cosmetic composition and a food composition containing said plant extract.
The plants which can be used to obtain the extract according to the invention include generally all the cereals (wheat, barley, rye, oats, corn, sorghum), with wheat being preferably used. Certain beans of dicotyledone plants (soy beans, peanuts), the mesocarp of the fruits of the oil-palm fruits and of the fruits of the avocado tree, as well as leaves rich in chromoplasts of spinach, cabbage and peas can also be used.
The protein portion of wheat grains contains from 5 to 10% lipids in the form of vesicles embedded in a protein network. These lipids include 70% of polar lipids. It is preferable to carry out the extraction on wheat grains, because an extract rich in di-O-D-galactosyl-di-O-acylglyceride can then be obtained.
The exact composition of the extract according to the invention depends of course on the nature and on the origin of the plant material: for example, it is well known that soy beans have a content of di-O-D-galactosyl-di-O-acylglyceride which is substantially lower than wheat, but the extract can generally contain between 10 and 50% Dgdg.
Concerning the preparation method, owing to the use of cold ethanol, it enables the extraction of the surface lipid fraction, as well as that of the lipids bound to the protein network. The choice of the ratio of the weight of the plant material to the weight of the solvent medium is important for the quality of the final product obtained and for the yield of the extraction. Preferably, the weight ratio in the method according to the present invention is of about one part of plant material to at least five parts of solvent medium.
The plant material is preferably provided as a powdered material obtained by the grinding of cereal grains, of the mesocarp or of the leaves of plants.
According to a first version, the extract from cereals according to the invention is provided in the form of an oil comprising (in percent weight):
According to a second version, the extract from cereals according to the invention is provided in the form of a powder comprising (in percent weight):
On the other hand, the plant extract according to the invention can be used for its inhibitory action against human elastase and collagenase, as a wound-healing agent, as a moisturising agent and/or as a free radical scavenger, and also as a means for enhancing the proliferation of skin fibroblasts. Furthermore, this extract can be used as a means (vector) for introducing cosmetically or pharmaceutically active agents into the intercellular space of the conjunctive tissue of the skin. Accordingly, one can use the extract, for example, for the preparation of dermatological compositions, of cosmetic compositions, of pharmaceutical compositions and/or of veterinary preparations for wound-healing and/or for treating skin problems.
Finally, the plant extract rich in Dgdg and in sphingolipids according to the invention has dietetic properties which are very interesting. The product is obtained from wheat, which, from a toxicological standpoint, is recognised as being without risk and no other solvent than ethanol is used for its extraction. Accordingly, a plant extract is obtained which makes it possible to retard skin ageing (by its moisturising action, elastase and collagenase inhibiting action) and reinforce the body defences against free radicals. The plant extract according to the invention can easily be dispersed in water or in a liquid dietetic preparation. Its addition to drinks necessitates no special method.